Phase change memory (PCM) is a type of nonvolatile memory in which a variable phase of a phase change element is employed to represent a unit of data, such as a bit of data. By reversibly switching the variable phase between a crystalline state and an amorphous state, the data state of the data unit can be switched. The variable phase of the phase change element can be reversibly switched by, for example, the application of different heating levels corresponding to the different phase states. Phase change memory is also known as phase random access memory (PRAM), phase change random access memory (PCRAM), ovonic unified memory, chalcogenide random access memory (or C-RAM), etc.